Apparatus for measuring the moisture content of materials



Ndv. 6, 1928. 1,690,155 A s. s. AMDURSKY v APPARATUS FOR MEASURING THE MOISTURE CONTENT OF MATERIALS Filed Nov. 19, 1926 INYENTOR QM My otherland th'us caused to sweep over the-web,-

Patented Nov. 6, 1928;

UNITED. STATES SAMUEL S. .AMDURSKY, OF ROCHESTER, .NEW YORK.

APPARATUS. FOR MEASURING THE MOISTURE CONTENT OF MATERIALS.

Application filed November 19, 1926. Serial Ito-149,483.

This invention relates generally to apparatus for measuring the moisture content of materials and more in particular. to a simple and eflicient form of apparatus for supplying'air having definite wet and dry bulb temperatures.

' For a full understanding of the invention, the principles of operation upon which it is based and its application, reference is made to the accompanying drawings in which Fig. 1 is an elevation, partly in section, of a device constructed according to the invention. a I

Fig. 2 is a sectional View of a detail shown in Fig. 1; and

Fig. 3 is a what I now consider. the principal application of the invention.

The invention relates more particularly to apparatus for determining and recording the humidity of the web'of paper, at any selected point between the wet end of the forming mechanism and the calender rolls, in accordance with the principles of the invention forming the subject matter of the application of George S. Witham, J r. Serial No. 531,863. In Fig. 3, 1 represents a web of paper which may be assumed to be a section of a contin uous web passing from the usual battery of drier rolls to the so-called sweat drier roll, or at any rate a section of the web at a point where the moisture content of the web is an important factor. To indicate or measure the moisture content of the paper at a desired point, an open sided box 2 is disposed across the web at that, point so that the open side is substantially closed by the web. Air is passed through the box from one end to the taking up moisture from the latter. If the moisture content of the air before andafter it is passed through the box', respectively, is measured, the difference is a criterion of the moisture content of the paper.

lVhilc the humidity of atmospheric air may be relatively constant over longer or shorter periods, depending upon the climatic conditions of different places, variations in humidity, if not noticed or taken into account will cause errors in the indications. It is thus necessary to make almost continuous measurements to determine the humidity of the air to be used.

To avoid this inconvenience and practical drawback, I propose to precondition the air so as to have a substantially constant degree ature.

diagrammatic View illustrating I of humidity ata definitedry bulb temperhe indications-otthe moisture content of the air after passing through the box 2 are then absolutely reliable and the necessity of continuously making computations to correct for variations in the humidity of the atmospheric air is thus obviated. Atmos- I pheric air is forced through the conditioner 3 by means of a fan 4 or the like and the condi-- tioned air. then passes through a conduit 5 into the box 2. The air from the other end of the box is'passed by means of a conduit 6. to a hygrometric device 7' referably of the 'wet and dry bulb type. he capillaries 8 and 9 lead from the two bulbs to an instrument 10 which may be an indicator, a regulator, or a recorder, as is well understood.-

The conditioning device, shown more in detail in Fig. 1, comprises a casing 11 having an air inlet 12 near the bottom and an outlet 20 at the top. Air is forced through the casing by means of a fan 4:. Near the bottom are disposed a nozzle 13 fed by a pipe 13 for delivering a fine spray of water and a nozzle 14 fed by a pipe 14: for delivering. steam to the conditioner. The purpose of the'twonoz zles is to produce by their cooperation air saturated to amaximum extent at a definite temperature. The nozzle 13 may be adjusted so that the water spray or mist formed is more than sufiicient to cause full saturation of the incoming air at the particular temperature. The steam supply to the steam nozzle is regulated by means of a valve 14*. The steam supplies the heat units necessary to maintain the required temperature. The regulation of the valve 14:is effected in the particular arrangement shown by means of a pressure operated mechanism 15 of the diaphragm type: which in turn is controlled by a bulb 16 extending into the zone of saturated air abovethe nozzles 13 and 14.. Since the air is fully saturated so that the wet bulb and dry bulb temperature indications are substantially the same, a single bulb, which in this case is a plain bulb, is sutlicient. The bulb diaphragm 15. In proportion as the temperat-ure of the saturated air decreases, the valve 14 operates to admit more steam and conversely rise of temperature causes a corresponding decrease in the steam admission,

with the result that that temperature remains substantially constant at a definite value for which the regulator is set.

Thus the water and steam nozzles co-operate to saturate the incoming air to a maximum extent and to automatically maintain the temperature of the saturated air passing upward- Y through the casing at a definite value.

Below the outlet 20 there is disposed within the casing 1 a device for heating the humidified air. This heating device may be of any desired construction and in the particular arrangement disclosed comprises a ration.

plurality of pipes 18 provided with heatradiating fins 18. The pipes are preferably connected in multiple between manifolds 19 connected to an inlet conduit 21 and an outlet conduit 22 respectively for passing steam or other fluid heating medium through the pipes. The heating operation is controlled by a regulating valve 23 preferably in the outlet conduit 22, which valve is in turn controlled by a bulb 24 operatively connected through the capillary 24 to the regulator 25 containing mechanism responsive to'the pressure conditions in the bulb 24 for controlling a fluid pressure conduit 26 for the operation of the diaphragm 27, which similar to the diaphragm 15, operates the valve 23.

The regulating" mechanism is so arranged that the valve 23 operates to admit more steam when the temperature drops and to restrict the admission of'steam when the temperature increases. The temperature of the air thus remains substantially constant. A single bulb is sufficient for the purpose, and 011 this reason the bulb 24 is also a plain I prefer to place the control valve 23 into the steam outlet whereby the temperature changes incident to the closing of the valve 23 are not abrupt but gradual and bring about a better regulation.

In addition to the bulbs 16 and 24, there are corresponding bulbs 28 and 29 for connection with an indicator or a recorder. At the bottom of the casing is a drain 30. 4

The operation, briefly expressed, is as follows: Air of any degree of relative humidity is drawn into the conditioner 3 and due to the combined action of a spray of water and steam is brought to and maintained at a definite temperature at substantially full satu- The regulation by means of valve 14* in dependence of the bulb 16 maintains this definite temperature. I

The heat transmitted to the humidified air through pipes 18 raises the temperature thereof and at the same time decreases its relative humidity. The air leaving the conditioner 3 thus has a substantially constant relative humidity at a definite substantially constant temperature.

The conditioner thus is instrumental in passing into contact with a web of paper air of constant relative humidity at a constant temperature and since the conditioned air is passed over a constant area of the paper at a velocity which can be readily kept constant, all the requirements are satisfied for obtaining reliable indications independently of variations in the relative humidity of the air and also independent, within wide limits, of temperature changes of the atmosphere from which the air is taken for conditioning.

, I claim:

.1. In apparatus for determining the humidity of a material, the combination with means for maintaining a flow of air into and out of contact with a surface of the material and means for measuring the moisture content of the air after contact, of means for acting upon the air prior to contact with said surface to impart to it a definite degree of relative humidityeat a definite temperature.

2. In apparatus of the class described, the combination of a tubular casing having an inlet at one end, an outlet at the opposite end and means for producing a flow of air through the casing. of means for treating the air flowing through the casing to impart to it a substantially constant degree of relative humidity and a substantially constant temperature at the outlet of the casing, including means for discharging a spray of water and steam into the casing, means for controlling the relative rate of discharge of water and steam to saturate the air at a substantially constant temperature, means for heating the air thus treated and means for controlling the heating operation to maintain the air flowing out of the casing at a substantially constant temperature.

3. In apparatus of the class described, the combination with means for producing a current of air, of means for discharging a spray of water into the current of air, a source of steam, means for admitting steam to the spray of water and means responsive to the temperature of the water for regulating the admission of steam so as to maintain the temperature of the water substantially constant, the rate of discharge of the water being such as to impart to the air a maximum degree of humidity at the temperature level at which the water is maintained by the steam and means for heating the current of humidified air to a substantially constant temperature.

In testimony whereof I aflix my signature.

SAMUEL S. AMDURSKY. 

